Investigation of Dowel Bar Placement Accuracy with a Dowel ...
Burke Lockable Dowel€¦ · Lockable Dowels improve site access, minimize formwork requirements...
Transcript of Burke Lockable Dowel€¦ · Lockable Dowels improve site access, minimize formwork requirements...
• Eliminates Pour Strips • Considerable Savings in Time and Material • Improves Safety
Revolutionizing Temporary Movement Joints
commonly found in closure strips of post-tension concrete projects.
Burke Lockable Dowel
2LOCKABLE DOWELS
The Burke Lockable Dowel has been designed for use at temporary move-
ment joints, most commonly found in post-tensioned concrete frames.
These dowels allow initial shrinkage of the concrete to take place and are
then locked in position with a mechanical plate and a controlled amount
of epoxy resin. The locked dowels continue to transfer shear, but prevent
further movement taking place.
ADVANTAGES
The use of Burke Lockable Dowels can save a significant amount of time
and materials over other construction methods. Concrete shrinkage has tra-
ditionally been accommodated by leaving gaps in the slab called “pour
strips” or “closure strips.” These strips are filled once movement has stabi-
lized, however until they are filled the slabs must be shored, restricting site
access and delaying site progress. Gaps in the slab also create a hazard for
site workers, use additional formwork and leave the soffit face marked.
Lockable Dowels improve site access, minimize formwork requirements
and accelerate the rate of construction. With a Lockable Dowel, there is
less requirement for the slabs to be shored or a support corbel to be
constructed, as shear load is transferred by the dowel. The time saved by
early removal of slab props can be significant.
A Lockable Dowel also provides many advantages over the site-assembled
arrangement of carbon steel reinforcing bar, galvanized or plastic ducting, vent
tubes and a non-specific grout, which is sometimes used by contractors.
In addition, engineers have found the Burke Lockable Dowel to be the
preferred design solution for pin-ended joints. Although it is customary for
practical reasons to use U-bars or other rebar continuity systems at these
connections, these options do not truly act as hinges and so rotation of the
slab under load can induce cracking at the wall-to-slab interface with
potential integrity issues.
The Lockable Dowel is closer to a true pin-ended joint and, being manu-
factured from stainless steel, provides additional corrosion protection over
systems using carbon steel reinforcement.
Burke Lockable Dowel
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REVOLUTIONIZING POST-TENSIONED PRECAST CONCRETE
Preliminary Pour Using the Burke Lockable Dowel
Finished Slab Using the Burke Lockable Dowel
Traditional Pour Strip
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APPLICATIONS
In most cases, Burke Lockable Dowels can be used to replace pour strips
at temporary movement joints in post-tensioned concrete frames. Burke
Lockable Dowels and DSD Shear Load Connectors (see Page 10) are
available for use at slab joints and retaining / core walls.
“Due to the long length of the parking structure’s concrete floor system,
planning for volumetric changes due to elastic shortening, creep and
shrinkage was essential. Meadow Burke’s Lockable Dowel ESDQ-L20
provided an innovative means to a traditional closure strip pour by
providing a temporary slip connection with the added benefit of reducing
the total number of permanent joints in the concrete floor system.”
Josh B. Hamby, PE, LEED AP Kimley-Horn and Associates, Inc.
Burke Lockable Dowel
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SLAB-TO-SLAB
Burke Lockable Dowel
Proven performance Minimal material usage
Various site-assembled components
Unreliable performance, additional construction materials used and support corbel required
SLAB-TO-WALL
Burke Lockable Dowel
Improved site access Reduced shoring time Simple installation Eliminates framework obstacles
Pour strip at wall-to-slab junction
Pour strip in slab
Burke Lockable Dowel
Proven performance Minimal material usage Simple installation Improved on-site safety
Additional formwork, trip hazard and restricted access Slabs shored for several weeks
Restricted access Slabs shored for several weeks
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RANGE OF LOCKABLE DOWELS
A Lockable Dowel allows initial shrinkage of the
concrete to take place and then, after a predetermined
time period (generally 30 to 90 days), is locked in position
with a mechanical plate and a controlled amount of epoxy
resin. The range comprises three products; ESDQ-L20,
HLDQ-L30 and ESDQ-L20W.
SLAB-TO-SLAB LOCKABLE DOWELS
ESDQ-L20*
The dowel component is manufactured from 30mm
diameter stainless steel; one end is threaded with a fixed
nut and washer, and the other features a series of grooves
to accept the Locking Plate. The cylindrical sleeve which
accepts the dowel component is contained within a
box-section to allow lateral, longitudinal and some
rotational movement. The epoxy resin is poured into the
L-shaped void former. This product has a design capacity
of almost two quarts. See pages 6-9 for full technical details.
SLAB-TO-WALL LOCKABLE DOWEL
ESDQ-L20W*
The dowel component is manufactured from 30mm
diameter stainless steel, but is shorter than the ESDQ-L20
dowel. One end of the dowel is designed to thread into the
stainless steel Burke SKS24 Threaded Anchor cast into the
face of the concrete and the other end features a series
of grooves to accept the Locking Plate. The sleeve
component is the same as used in the ESDQ-L20. See
pages 6-9 for full technical details.
HLDQ-L30*
The HLDQ-L30 is a high load Lockable Dowel with a
design capacity of up to 30.6 kips. See pages
6-9 for full technical details.
ESDQ-L20 for Slab-to-Slab
Locking Plate
Dowel Component
Dowel Component
SKS24 Threaded Anchor supplied with a nailing plate
Sleeve Component featuring void former supplied with label on nailing plate
Sleeve Component featuring void former supplied with label on nailing plate
Sleeve Component featuring void former supplied with label on nailing plate
Dowel Component
Locking Plate
Locking Plate
ESDQ-L20W for Slab-to-Wall
HLDQ-L30 for Slab-to-Slab
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Burke Lockable Dowel
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SLAB-TO-WALL APPLICATION
EPOXY RESIN
Each dowel is locked after a pre-determined time period (generally 3-4
weeks) with a high quality, two-part epoxy resin. The resin is mixed and
poured into the L-shaped void former. Each dowel requires 1,500g of resin
which can be supplied either in a single can for one application or bulk
packaging for locking multiple dowels.
Two-part Epoxy Resin supplied with: ESDQ-L20 ESDQ-L20W HLDQ-L30
“The Burke Lockable Dowel is a very clean system compared to pour strips. Pour strips are a nightmare! Pour strips are a mess with all the shoring, safety concerns, cables, cleaning, fill up, and conduit problems. Any extra money spent on the Lockable Dowel is well worth the benefit. The Lockable Dowel saved about 3 weeks with this project. The Lockable Dowel is so clean no one noticed there was a pour strip. If you have encountered pour strips before, the Lockable Dowel is a no brainer. You would be crazy not to use it!“ Mahmoud Farawi Skanska USA Raleigh, NC
Burke Lockable Dowel
www.MeadowBurke.com
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PERFORMANCE DATA
ESDQ-L20 EXAMPLE Slab Thickness = 10" Joint Width = 3/4" Concrete Strength = 4,000 psi Actual Load = 6,000 lbf/ft Allowable Vertical Design Load = 14.0 kip (10" slab 3/4" joint) Therefore Centers for Vertical Load = 14.0 / 6.0 = 2.33' use 28" centers Each dowel will in addition provide an allowable tension across the joint of 22.5 kip (for slab to wall this is 18.0 kip), therefore the total allowable tension in the direction of the dowel = 22.5 kip / (28/12) = 9.6 kip/ft (for slab-to-wall 18.0 kip/ (28/12) = 7.7 kip/ft). If this is insufficient, the dowel centers can be reduced to a minimum of 1.5 x slab thickness to increase the allowable tension across the joint, in this example it would increase to 22.5 / (15/12) = 18.0 kip/ft (for slab-to-wall 18.0 kip/ (15/12) = 14.4 kip/ft).
Slab Thickness Design Strength Longitudinal Load Vertical Design Strength (kip) for Various Design Joint Widths in 4000 psi Concrete
in. 6.25 6.50 7.00 7.50 8.00
8.625 9.00
10.00 11 & Above
kip 10.0 10.0 14.6 14.6 18.0 22.5 22.5 22.5 22.5
1/4" 2.7 3.4 5.1 5.6 9.0 12.0 13.0 14.0 15.7
1/2" 2.7 3.4 5.1 5.6 9.0 12.0 13.0 14.0 15.7
3/4" 2.7 3.4 5.1 5.6 9.0 12.0 13.0 14.0 14.9
1" 2.7 3.4 5.1 5.6 9.0 12.0 12.8 14.0 14.2
1 1/4" 2.7 3.4 5.1 5.6 9.0 12.0 12.2 13.6 13.6
1 1/2" 2.7 3.4 5.1 5.6 9.0 12.0 11.8 13.0 13.0
2" 2.7 3.4 5.1 5.6 9.0 10.8 10.8 12.4 12.5
ESDQ-L20 LOCKABLE DOWEL (SLAB-TO-SLAB)
Slab Thickness Design Strength Longitudinal Load Vertical Design Strength (kip) for Various Design Joint Widths in 4000 psi Concrete
in. 6.25 6.50 7.00 7.50 8.00
8.625 9.00
10.00 11 & Above
kip 10.0 10.0 14.6 14.6 18.0 18.0 18.0 18.0 18.0
1/4" 2.7 3.4 5.1 5.6 9.0 12.0 13.0 14.0 15.7
1/2" 2.7 3.4 5.1 5.6 9.0 12.0 13.0 14.0 15.7
3/4" 2.7 3.4 5.1 5.6 9.0 12.0 13.0 14.0 14.9
1" 2.7 3.4 5.1 5.6 9.0 12.0 12.8 14.0 14.2
1 1/4" 2.7 3.4 5.1 5.6 9.0 12.0 12.2 13.6 13.6
1 1/2" 2.7 3.4 5.1 5.6 9.0 12.0 11.8 13.0 13.0
2" 2.7 3.4 5.1 5.6 9.0 10.8 10.8 12.4 12.5
ESDQ-L20W LOCKABLE DOWELS (SLAB-TO-WALL)
Slab Thickness Design Strength Longitudinal Load Vertical Design Strength (kip) for Various Design Joint Widths in 4000 psi Concrete
in. 9.50 & above
kip 22.5
1/4" 30.6
1/2" 30.6
3/4" 30.6
1" 30.6
1 1/4" 30.6
1 1/2" 30.6
2" 30.6
HLDQ-L30 LOCKABLE DOWELS (SLAB-TO-SLAB)
Movement Locked
Load transfer between slabs
Vertical load transfer between slabs
Vertical load transfer between slabs
All values in the tables above are design load capacities (LRFD) and have to be compared to factored loads.
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Burke Lockable Dowel
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DIMENSIONS
ESDQ-L20 COMPONENTS DOWEL COMPONENT
SLEEVE COMPONENT
HLDQ-L30 COMPONENTS DOWEL COMPONENT
SLEEVE COMPONENT
ESDQ-L20W COMPONENTS SKS24 THREADED ANCHOR
SLEEVE COMPONENTDOWEL COMPONENT
EDGE DISTANCE AND SPACINGS For connectors working at or near their maximum capacity, the minimum spacing should be 1.5 times the slab thickness. Where the design load of the connector could be used in a thinner slab, a spacing of 1.5 times the thinner slab thickness can be used. The minimum end distance is always 0.5 times the spacing.
1-3/16"1-1/4" Internal
Diameter 6-1/2"
5-1/2"
1-5/8"
4-1/16"
1-3/16"
10-1/2"M30x3.5mm
3-5/8"
6"
1-3/16"
10-1/2"
19"4-1/2"
18" 9-1/2"
1-1/4" Internal Diameter
6-1/2"
11"
Max 1-1/2" Lateral Movement
5-1/2"
7" 1/4"1/4"
Max 1-1/2" Lateral Movement
4-1/2"
1-1/4" Internal Diameter 6-1/2"
9-1/2"
1-1/2" Lateral Movement 4"
4-1/2"
h
10" min.
min. 0.75h min. 1.5h
min. 0.75h min. 1.5h
7-1/2" min. 15" min.
ESDQ-L20 Minimum Edge Distance and Spacings
HLDQ-L30 Minimum Edge Distance and Spacings
ESDQ-L20W Minimum Edge Distance and Spacings
ESDQ-L20 EXAMPLE Slab Thickness = 12" Joint Width = 1" Concrete Strength = 4,000 psi Allowable Load/Connector = 14.2 kip/ft (based on slabs 10" and above) Spacing for Max. Load 12" x 1.5 = 18" End Distance for Max. Load 18" x 0.5 = 9" Allowable Load/Foot = 14.2 kip/ (18/12) = 9.5 kip/ft As an ESDQ L20 can be used in a 7" slab for a reduced allowable load per connector of up to 9,500 lbf, the spacing can be based on a 7" slab. Therefore: Reduced Spacing 7" x 1.5 = 10-1/2" Reduced End Distance 10-1/2" x 0.5 = 5-1/4" Allowable Load/Foot 9.5 kip/ (10-1/2"/12) = 10.8 kip/ft
4"
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Burke Lockable Dowel
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REINFORCEMENT DETAILS Local reinforcement is required around each Burke Lockable Dowel to guarantee that the forces are transferred between the connectors and the concrete. Correct detailing in accordance with appropriate design codes and the recommendations provided here will ensure the dowels attain their
full capacity. The tables show the main reinforcement required, together with details of reinforcement above and below the connectors. Although only the sleeve components are illustrated, the same reinforcement is required around the dowel component.
Longitudinal reinforcement above
connector
Longitudinal reinforcement below
connector
Longitudinal reinforcement below
connector
Longitudinal reinforcement above
connector
Main reinforcement each side
Longitudinal reinforcement above
connector
Longitudinal reinforcement below
connector
Longitudinal reinforcement above
connector
Longitudinal reinforcement below
connector
ESDQ-L20
HLDQ-L30
Lockable Dowel Reference
Minimum No. of U-bars each Side
ESDQ-L20 HLDQ-L30
#4 2 4
#5 – 3
OPTIONS FOR MAIN REINFORCEMENT
Lockable Dowel Reference
Minimum No. of Bars Top and Bottom
ESDQ-L20 HLDQ-L30
#4 2 2
#5 – 2
OPTIONS FOR LONGITUDINAL REINFORCEMENT
ESDQ-L20
HLDQ-L30
Main reinforcement each side
Wall Elevation
Vertical additional #5 rebar to be 4’ – 0’, centered on dowel
Wall Section View Wall Plan View
8" max1-1/2" (TYP.)
1-1/2" (TYP.)
Main Wall Reinf. (TYP)
Wall Thickness Wall Thickness
Main Wall Reinf. (TYP)
1-1/2"
1-1/2"
2"
2"
Main Wall Reinf. (TYP)
Add’l #5 (TYP)
Add’l #5 (TYP)
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Burke Lockable Dowel
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INSTALLATION
SLAB-TO-SLAB: Although installation is shown for the ESDQ-L20, the procedure is the same for the HLDQ-L30.
SLAB-TO-WALL
Notes: Where deep concrete pours are proposed, the installation will require further consideration. More robust fixing of the sleeve and dowel components will be necessary, to avoid displacement during casting of the concrete.
Nail the sleeve to the formwork either central in the slab or for slab depths over 12" so the top of the grout box is level with the top of the slab. Do not remove the label over the nailing plate as this prevents ingress of concrete into the sleeve. Fix the local reinforcement.
Pour the concrete, and when of sufficient strength, strike the formwork. Puncture the label to reveal the cylindrical sleeve only and insert the dowel until it is completely installed to the back of the grout box.
Fix the local reinforcement around the dowel component and pour the concrete.
After a predetermined time period (generally 60-120 days), when movement between the slabs has stabilized the dowel is ready to be locked. Fit the Locking Plate on a groove in the center of the grout box. The fan-shaped Locking Plate allows the dowel to be locked in any position.
Mix the two-part epoxy resin and pour into the grout box, ensuring it flows along the stainless steel box section towards the joint.
After 24 hours the grout box can be filled with cementitious material, level with the top of the slab, to complete the installation. The locked dowel continues to transfer vertical load between the slabs, but movement can no longer take place.
Nail the threaded anchor to the formwork so the dowel will be central in the adjoining slab or within 6" of the top of slabs over 12". Fix the local reinforcement and cast the concrete.
When concrete reaches sufficient strength, strike the formwork and remove nailing plate. Screw the dowel into the anchor.
Puncture the label of the sleeve to reveal the cylindrical sleeve only. Push the sleeve over the dowel until the sleeve front is touching the wall. Tie sleeve to reinforcement and pour concrete.
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64 5
32
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1
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BURKE DSD SHEAR LOAD CONNECTOR: The perfect complement to the Lockable Dowel
Reinforced concrete is an important construction material. It offers strength,
durability and can be formed into a variety of shapes. Concrete structures
are designed with expansion and contraction joints to allow movement
to take place. Dowels are used to transfer shear load across these joints.
The Burke DSD Shear Load Connector, is the perfect complement to the
Lockable Dowel. The Burke DSD offers significant advantages over plain
dowel bars. They are more effective at transferring load and accommodat-
ing movement and, due to their two-part construction, are more simple to
install. Meadow Burke offers solutions for many issues encountered in
cast-in-place construction.
The DSD range of connectors offers significant advantages over plain
dowels. Each connector is a two-part assembly comprising a sleeve and a
dowel component. Installation is a fast and accurate process and drilling
of either formwork or concrete is not required. The sleeve is simply nailed
to the formwork ensuring subsequent alignment with the dowel, which is
essential for effective movement.
These connectors are manufactured from stainless steel to ensure a high
degree of corrosion resistance with no requirement for additional protection.
The Burke DSD allows permanent joint movement. It works flawlessly in beams crossing the intended pour strips. By utilizing the Burke DSD, the pour
strip is reduced across the entire depth of the slab.
11Dowels are used to transfer shear
across construction and movement
joints in concrete. They are often
either cast or drilled into the
concrete. A single row of short
thick dowels provides reasonable
shear transfer but suffers from
deformation. This can lead to
stress concentrations, resulting
in subsequent breaking of the
concrete.
Where dowels are used across expansion and contraction joints, half the
length of the bar is de-bonded to allow movement to take place.
Dowelled joints either require formwork to be drilled for the dowels to pass
through, or concrete to be drilled for dowels to be resin fixed in one side.
At movement joints, dowels will need to be accurately aligned in both
directions to ensure movement can actually take place, otherwise cracking
is likely to occur.
BURKE DSD
The Burke DSD is the original two-part, double dowel, shear load connector
with the two dowels manufactured from Duplex stainless steel bar. The
dowel component can move longitudinally within the sleeve to accommo-
date movement. The connector is available in 10 standard sizes and has
design capacities from approximately 4,500 lbs to more than 214,000 lbs.
The larger connectors can be used in joints up to 60mm wide, while larger
joints can be accommodated using special dowels. Please contact Burke’s
Technical Department for further information.
Using Burke DSD's in Beams in conjunction with slab-to-slab Burke Lockable Dowels
Burke Lockable Dowel
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Innovating Concrete Constructionwww.MeadowBurke.com
MB1118
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